U.S. patent number 8,813,697 [Application Number 13/900,020] was granted by the patent office on 2014-08-26 for air spring system for an internal combustion engine.
This patent grant is currently assigned to BRP-Powertrain GmbH & Co. KG. The grantee listed for this patent is BRP-Powertrain GMBH & Co. KG. Invention is credited to Christian Berger, Werner Brandstaetter, Michael Dopona, Roland Ennsmann, Stefan Leiber, Johann Neuboeck, Roland Spatzenegger, Gerhard Wiesinger.
United States Patent |
8,813,697 |
Dopona , et al. |
August 26, 2014 |
Air spring system for an internal combustion engine
Abstract
A method of supplying air to an air spring biasing one of an
intake valve and an exhaust valve of an internal combustion engine
to a closed position is disclosed. The method includes: driving an
air compressor with a motor prior to starting of the internal
combustion engine, the air compressor fluidly communicating with
the air spring to supply air to the air spring; determining that a
predetermined condition has been reached; starting the engine once
the predetermined condition has been reached; and driving the air
compressor with a rotating shaft of the engine once the engine has
started.
Inventors: |
Dopona; Michael (Wartberg,
AT), Neuboeck; Johann (Gunskirchen, AT),
Brandstaetter; Werner (Meggenhofen, AT), Berger;
Christian (Meggenhofen, AT), Ennsmann; Roland
(Gunskirchen, AT), Wiesinger; Gerhard (Lenzing,
AT), Leiber; Stefan (Marchtrenk, AT),
Spatzenegger; Roland (Bad Hall, AT) |
Applicant: |
Name |
City |
State |
Country |
Type |
BRP-Powertrain GMBH & Co. KG |
Gunskirchen |
N/A |
AT |
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Assignee: |
BRP-Powertrain GmbH & Co.
KG (Gunskirchen, AT)
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Family
ID: |
42105871 |
Appl.
No.: |
13/900,020 |
Filed: |
May 22, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130276729 A1 |
Oct 24, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12690545 |
Jan 20, 2010 |
8550044 |
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61145876 |
Jan 20, 2009 |
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Current U.S.
Class: |
123/90.14;
417/384; 123/90.16 |
Current CPC
Class: |
F02B
77/00 (20130101); F01L 9/16 (20210101); F01L
1/465 (20130101); F02B 21/00 (20130101); F01L
2800/01 (20130101) |
Current International
Class: |
F01L
9/02 (20060101) |
Field of
Search: |
;123/90.14,90.16
;417/384 |
References Cited
[Referenced By]
U.S. Patent Documents
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671808 |
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Sep 1989 |
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CH |
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10113095 |
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Sep 2002 |
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DE |
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0396327 |
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EP |
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0646700 |
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Mar 1999 |
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EP |
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EP |
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569131 |
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2102065 |
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63009609 |
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JP |
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2230909 |
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2283806 |
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JP |
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2294506 |
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JP |
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3194103 |
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JP |
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5039704 |
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JP |
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5052103 |
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JP |
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5059916 |
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JP |
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5079307 |
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JP |
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6159024 |
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JP |
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6248912 |
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JP |
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10288012 |
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Oct 1998 |
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JP |
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2003222011 |
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JP |
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Nov 2007 |
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JP |
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0149980 |
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Jul 2001 |
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WO |
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2009087441 |
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Jul 2009 |
|
WO |
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|
Primary Examiner: Chang; Ching
Attorney, Agent or Firm: BCF LLP
Parent Case Text
CROSS-REFERENCE
The present application is a divisional application of U.S. patent
application Ser. No. 12/690,545, filed Jan. 20, 2010, which claims
priority to U.S. Provisional Patent Application No. 61/145,876,
filed Jan. 20, 2009, the entirety of both of which is incorporated
herein by reference.
Claims
What is claimed is:
1. A method of supplying air to an air spring biasing one of an
intake valve and an exhaust valve of an internal combustion engine
to a closed position comprising: driving an air compressor with a
motor prior to starting of the internal combustion engine, the air
compressor fluidly communicating with the air spring to supply air
to the air spring; determining that a predetermined condition has
been reached; starting the engine once the predetermined condition
has been reached; and driving the air compressor with a rotating
shaft of the engine once the engine has started.
2. The method of claim 1, wherein the predetermined condition is a
predetermined amount of time for which the air compressor is driven
by the motor.
3. The method of claim 1, wherein the predetermined condition is a
predetermined air pressure indicative of an air pressure inside the
air spring.
Description
FIELD OF THE INVENTION
The present invention relates to an air spring system for an
internal combustion engine.
BACKGROUND OF THE INVENTION
Many internal combustion engines, such as engines operating on the
four-stroke principle, have intake and exhaust valves provided in
the cylinder head of the engine. The intake valves open and close
to selectively communicate the air intake passages of the engine
with the combustion chambers of the engine. The exhaust valves open
and close to selectively communicate the exhaust passages of the
engine with the combustion chambers of the engine.
To open the valves, many engines are provided with one or more
camshafts having one or more cams provided thereon. The rotation of
the camshaft(s) causes the cam(s) to move the valves to an opened
position. Metallic coil springs are usually provided to bias the
valves toward a closed position.
Although metallic coil springs effectively bias the valves toward
their closed positions for most engine operating conditions, at
high engine speeds, the metallic coil springs have a tendency to
resonate. When resonating, the metallic coil springs cause the
valves to vacillate between their opened and closed positions,
which, as would be understood, causes the intake and exhaust
passages inside which the valves are connected to be opened when
they should be closed. This results in a reduction of operating
efficiency of the engine at high engine speeds.
One solution to this problem consists in replacing the metallic
coil springs with air springs. An air spring typically consists of
a cylinder having a piston therein. An air chamber is defined
between the cylinder and the piston. The valve (intake or exhaust)
is connected to the piston of the air spring. When the cam moves
the valve to its opened position, the piston of the air spring
moves with the valve, thus reducing the volume of the air chamber
and as a result increasing the air pressure therein. When the cam
no longer pushes down on the valve, the air pressure inside the air
chamber causes the piston of the air spring to return to its
initial position and to return the valve to its closed
position.
Air springs do not resonate at high engine speeds the way metallic
coil springs do. Also, for equivalent spring forces, air springs
are lighter than metallic coil springs. Furthermore, air springs
have progressive spring rates, which means that the spring force of
an air spring varies depending on the position of the piston inside
the cylinder of the air spring, which may also be advantageous for
certain engines.
Although air springs offer many advantages over metallic coil
springs, they also have some deficiencies that need to be
addressed.
One of these deficiencies is that during operation, some of the air
inside the air chamber of the air spring blows by the piston as the
piston moves to reduce the volume of the air chamber. As a result,
the air pressure inside the air spring is reduced, thus reducing
the spring force of the air spring. This results in the valve not
returning to its closed position as fast as it should, thus
reducing the efficiency of the engine. In extreme cases, it is
possible that the air pressure inside the air spring is
insufficient to return the valve to its closed position. Since the
valve remains in its opened position, the engine no longer operates
properly, and the piston of the engine can come into contact with
the valve, potentially damaging the valve.
One solution consists in providing a reservoir of pressurized air
in fluid communication with the air springs that replenishes the
air inside the air springs as it leaks out of the air springs.
However, the pressurized air inside the reservoir is eventually
depleted and the reservoir needs to be refilled or replaced. This
can prove to be inconvenient for the users of the vehicle or device
inside which the engine is provided.
Therefore, there is a need for a system for replenishing air inside
an air spring used to bias a valve of an engine that does not
require frequent replacement or refilling.
Another of the deficiencies associated with air springs is that
even when the engine is not is use, air can leak out of the air
springs. When the air pressure inside the air springs becomes too
low, this causes the valves to move to their opened positions. When
this occurs and the engine is started, the pistons of the engine
can come into contact with the valves, potentially damaging the
valves, and as a result preventing operation of the engine.
One possible solution consists in providing metallic coil springs
having a relatively low spring constant in addition to the air
springs. The metallic coil springs are strong enough to bias the
valves towards their closed position even when the air pressure
inside the air springs is no longer sufficient to do so on its own.
However, these metallic coil springs do not provide enough biasing
force to return the valves to their closed position fast enough
while the engine is in operation. Although the addition of these
metallic coil springs will prevent the pistons of the engine from
coming into contact with the valves when the engine is started,
they add weight and complexity to the air spring system. The
additional metallic coil springs can also lead to some resonance as
the speed of the engine increases.
Therefore, there is a need for a system for replenishing air inside
an air spring used to bias a valve of an engine before the engine
is started.
SUMMARY OF THE INVENTION
It is an object of the present invention to ameliorate at least
some of the inconveniences present in the prior art.
It is an object of the present invention to provide a method of
supplying air to an air spring biasing one of an intake valve and
an exhaust valve of an internal combustion engine to a closed
position. The engine has an air compressor for supplying air to the
air spring. The air compressor can be driven by a motor and by a
rotating shaft of the engine. The motor drives the air compressor
prior to engine start-up, and once the engine has started, the
rotating shaft of the engine drives the air compressor.
In one aspect, the invention provides a method of supplying air to
an air spring biasing one of an intake valve and an exhaust valve
of an internal combustion engine to a closed position. The method
comprises: driving an air compressor with a motor prior to starting
of the internal combustion engine, the air compressor fluidly
communicating with the air spring to supply air to the air spring;
determining that a predetermined condition has been reached;
starting the engine once the predetermined condition has been
reached; and driving the air compressor with a rotating shaft of
the engine once the engine has started.
In a further aspect, the predetermined condition is a predetermined
amount of time for which the air compressor is driven by the
motor.
In an additional aspect, the predetermined condition is a
predetermined air pressure indicative of an air pressure inside the
air spring.
Embodiments of the present invention each have at least one of the
above-mentioned objects and/or aspects, but do not necessarily have
all of them. It should be understood that some aspects of the
present invention that have resulted from attempting to attain the
above-mentioned objects may not satisfy these objects and/or may
satisfy other objects not specifically recited herein.
Additional and/or alternative features, aspects, and advantages of
embodiments of the present invention will become apparent from the
following description, the accompanying drawings, and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, as well as
other aspects and further features thereof, reference is made to
the following description which is to be used in conjunction with
the accompanying drawings, where:
FIG. 1 is a side elevation view of an internal combustion engine
according to the present invention;
FIG. 2 is an end elevation view of the engine of FIG. 1;
FIG. 3 is a perspective view of a first embodiment of internal
components of a cylinder head of the engine of FIG. 1;
FIG. 4 is a partial cross-sectional view of a valve, air spring,
and camshaft assembly of the engine of FIG. 1;
FIG. 5 is a perspective view of an air compressor of the engine of
FIG. 1;
FIG. 6 is a cross-sectional view of the air compressor of FIG. 5
taken along line 6-6 in FIG. 5;
FIG. 7 is a perspective view of a second embodiment of some of the
internal components of the cylinder head of the engine of FIG.
1;
FIG. 8 is a partial cross-sectional view of the components of FIG.
7;
FIG. 9 is a perspective view of the cylinder head of the engine of
FIG. 1 containing the internal components of FIG. 7, with the
cylinder head cover removed;
FIG. 10 is another perspective view of the cylinder head of the
engine of FIG. 1 containing the internal components of FIG. 7, with
the cylinder head cover removed;
FIG. 11 is a perspective view of covers of the cylinder head of
FIG. 9;
FIG. 12 is a logic diagram illustrating a method of supplying air
to an air spring of the embodiment show in FIG. 7;
FIG. 13 is a schematic diagram of an alternative embodiment of an
air spring system of the engine of FIG. 1; and
FIG. 14 is a logic diagram illustrating a method of supplying air
to an air spring of the embodiment show in FIG. 13.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An internal combustion engine 10 in accordance with the present
invention will be described with reference to FIGS. 1 to 3. The
engine 10 operates on the four-stroke principle, however it is
contemplated that aspects of the present invention could be used on
engines operating on other principles and having intake and/or
exhaust valves. The engine 10 has a crankcase 12. The crankcase 12
houses a crankshaft 14 and an output shaft 16. The output shaft 16
is operatively connected to the crankshaft 14 via a transmission
(not shown) also housed in the crankcase 12. The output shaft 16
extends out of the crankcase 12 to transmit power from the engine
10 to an element operatively connected to the output shaft 16. In
the case where the engine 10 is provided in a wheeled vehicle, such
as a motorcycle, the output shaft 16 is operatively connected to
the wheels of the vehicle to transmit power from the engine 10 to
the wheels. It is contemplated that the engine 10 could be used in
other types of vehicles, such as a snowmobile, or in other types of
applications.
A cylinder block 18 is connected to the crankcase 12. The cylinder
block 18 defines a cylinder 20. A piston 22 is disposed inside the
cylinder 20. The piston 22 is connected by a connecting rod 24 to
the crankshaft 14. During operation of the engine 10, the piston 22
reciprocates inside the cylinder 20 along a cylinder axis 26
defined by the cylinder 20, thus driving the crankshaft 14, which
drives the output shaft 16 via the transmission. It is contemplated
that the cylinder block 18 could define more than one cylinder 20,
and, as a result, the engine 10 would have a corresponding number
of pistons 22 and associated parts. It is also contemplated that
the engine could be a V-type engine having two cylinder blocks
18.
A cylinder head 28 is connected to the cylinder block 18. The
cylinder head 28 has two side walls 30, two end walls 32, and a
cylinder head cover 34. The cylinder head 28, the cylinder 20, and
the piston 22 define a variable volume combustion chamber 36 of the
engine 10 therebetween.
As seen in FIG. 3, two air intake passages 38 are provided in the
cylinder head 28. One end of each air intake passage 38 is
connected to the combustion chamber 36, and the other end of each
air intake passage 38 is connected to a corresponding outlet of an
air intake manifold 40 (FIG. 1) having a single inlet. A carburetor
42 (FIG. 1) is connected to the inlet of the air intake manifold
40. The carburetor 42 controls the flow of air and fuel that enters
the combustion chamber 36 via the air intake passages 38. It is
contemplated that the carburetor 42 could be replaced by a throttle
body that only controls the flow of air to the combustion chamber
36, in which case a fuel injector in communication with the
combustion chamber 36 would be provided in the engine 10. Each air
intake passage 38 is provided with an intake valve 44 that is
movable between an opened position and a closed position to allow
or prevent, respectively, air and fuel to enter the combustion
chamber 36 as described in greater detail below. Each intake valve
44 is provided with an air spring 45 that biases the intake valve
44 toward its closed position.
Two exhaust passages 46 are provided in the cylinder head 28. One
end of each exhaust passage 46 is connected to the combustion
chamber 36, and the other end of each exhaust passage 46 is
connected to a corresponding inlet of an exhaust manifold (not
shown) having a single outlet. The outlet of the exhaust manifold
is connected to an exhaust system of the engine 10 which releases
the exhaust gases from the engine 10 to the atmosphere. Each
exhaust passage 46 is provided with an exhaust valve 48 that is
movable between an opened position and a closed position to allow
or prevent, respectively, exhaust gases to exit the combustion
chamber 36 as described in greater detail below. Each exhaust valve
48 is provided with an air spring 49 that biases the exhaust valve
48 toward its closed position.
It is contemplated that there may be only one, or more than two, of
each of the air intake and exhaust passages 38, 46 with a
corresponding number of intake and exhaust valves 44, 48 and
associated elements. It is also contemplated that there may be a
different number of air intake and exhaust passages 38, 46. For
example, it is contemplated that there could be two air intake
passages 38 and a single exhaust passage 46. Also, although it is
preferred that each of the valves 44, 48 be provided with an air
spring 45 or 49, it is contemplated that only some of the valves
44, 48 (or only one of the valves 44, 48 should there be only one
intake valve 44 and/or one exhaust valve 48) could be provided with
an air spring 45 or 49.
An intake camshaft 50 is disposed in the cylinder head 28 generally
parallel to a rotation axis of the crankshaft 14. A sprocket 52 is
disposed at one end of the intake camshaft 50. A chain (not shown)
operatively connects the sprocket 52 to a sprocket (not shown)
operatively connected to the crankshaft 14, such that the intake
camshaft 50 is driven by the crankshaft 14. Two intake cams 54 (one
per intake valve 44) are disposed on the intake camshaft 50. Each
intake cam 54 engages a corresponding intake cam follower 56
rotatably disposed on an intake cam follower shaft 58. Each air
spring 45 is biased against its corresponding intake cam follower
56, such that, as the intake camshaft 50 rotates, each intake cam
54 pushes on its corresponding intake cam follower 56, which in
turn pushes on its corresponding air spring 45 and moves the
corresponding intake valve 44 to the opened position. As the intake
camshaft 50 continues to rotate, each air spring 45 returns the
corresponding intake valve 44 to its closed position.
An exhaust camshaft 60 is disposed in the cylinder head 28
generally parallel to the intake camshaft 50. A sprocket 62 is
disposed at one end of the exhaust camshaft 60. A chain (not shown)
operatively connects the sprocket 62 to a sprocket (not shown)
operatively connected to the crankshaft 14, such that the exhaust
camshaft 60 is driven by the crankshaft 14. Two exhaust cams 64
(one per exhaust valve 48) are disposed on the exhaust camshaft 60.
Each exhaust cam 64 engages a corresponding exhaust cam follower 66
rotatably disposed on an exhaust cam follower shaft 68. Each air
spring 49 is biased against its corresponding exhaust cam follower
66, such that, as the exhaust camshaft 60 rotates, each exhaust cam
64 pushes on its corresponding exhaust cam follower 66, which in
turn pushes on its corresponding air spring 49 and moves the
corresponding exhaust valve 48 to the opened position. As the
exhaust camshaft 60 continues to rotate, each air spring 49 returns
the corresponding exhaust valve 48 to its closed position.
It is contemplated that the cam followers 56, 66, and the cam
follower shafts 58, 68 could be omitted and that the cams 54, 64
could engage the air springs 45, 49 and valves 44, 48 directly. It
is also contemplated that the cam followers 56, 66 could be
replaced by rocker arms. It is also contemplated that each cam 54,
64 could engage more than one valve 44, 48. It is also contemplated
that there could be only one camshaft having both the intake and
exhaust cams 54, 64 disposed thereon. It is also contemplated that
the shape of the cams 54, 64 could be different from the one
illustrated in the figures depending on the type of engine
performance that is desired.
A spark plug 70 (FIG. 1) is disposed between the camshafts 50 and
60 and extends inside the combustion chamber 36 to ignite the air
fuel mixture inside the combustion chamber 36.
Turning now to FIG. 4, one of the air springs 49 will be described
in more detail. The other air spring 49 and the air springs 45 have
the same construction and as such will not be described in detail
herein. The air spring 49 includes a cylinder 72 and a piston 74
disposed inside the cylinder 72 to reciprocally move therein. The
top of the piston 74 is the portion of the air spring 49 which
comes into contact with the exhaust cam follower 66. An air chamber
76 is defined between the cylinder 72 and the piston 74. A cotter
78 disposed around the end of the exhaust valve 48 connects the
exhaust valve 48 to the piston 74 such that the piston 74 and the
exhaust valve 74 reciprocate together. A shim 80 is disposed
between the end of the exhaust valve 48 and the piston 74. The
thickness of the shim 80 is selected such that the exhaust valve 48
will properly sit in the inlet of the exhaust passage 46 when the
valve 48 is in its closed position and will extend to the desired
position when the valve 48 is in its opened position. A valve stem
guide 82 is integrally formed with the cylinder 72 and, as the name
suggests, guides the stem 84 of the exhaust valve 48 to ensure that
the exhaust valve 48 only moves along a straight line. An air port
86 is formed in the bottom 88 of the cylinder 72. The air port 86
is connected to an air supply line 90 used to supply air to the air
chamber 76 of the air spring 49 as described in greater detail
below. The air port 86 is dimensioned such that, as the piston 74
moves toward the bottom 88 of the cylinder 72, the air pressure
inside the air chamber 76 will increase and the piston 74 (and the
exhaust valve 48) will return to its initial position (due to the
air pressure) before enough air drains out via the air port 86 to
adversely affect the performance of the air spring 49.
Turning back to FIGS. 1 to 3, a first embodiment of the air spring
system of the engine 10 will be described. A compressor 100,
described in greater detail below, is disposed inside the cylinder
head 28. During operation of the engine 10, the compressor 100
supplies air to the air springs 45, 49 via the air supply line 90
so as to maintain the air pressure inside the air springs 45,
49.
The compressor 100 is held inside a compressor cover 102 (FIGS. 1
and 2) that is fastened over an aperture (not shown) formed in one
of the side walls 30 of the cylinder head 28. When the compressor
cover 102 is in place as shown in FIGS. 1 and 2, the air compressor
100 is disposed just below the intake camshaft 50 so as to be
driven by the intake camshaft 50, as will be described in more
detail below. It is contemplated that the air compressor 100 could
alternatively be driven by another rotating shaft of the engine 10,
such as the exhaust camshaft 60 or the crankshaft 14. By supporting
the air compressor 100 in the compressor cover 102, the air
compressor 100 can be removed from the cylinder head 28 without
having to remove the cylinder head cover 34 and the intake camshaft
50. Also, by locating the air compressor 100 inside the cylinder
head 100 below the intake camshaft 50, the packaging of the
cylinder head 28 and its components remains compact and maintenance
on the camshafts 50, 60, air springs 45, 49, and valves 44, 48 can
be done without having to remove the air compressor 100.
The air compressor 100 is a reciprocating air compressor, and more
specifically a piston-type air compressor. In order to reduce the
pressure pulses that are inherent from this type of compressor, air
from the air compressor 100 flows to an accumulator chamber 104
(schematically shown in FIG. 3) that is formed in the cover 102.
The accumulator chamber 104 is fluidly connected to the air supply
line 90 which supplies air, first to the air springs 45, then to
the air springs 49. The air supply line 90 connects the air springs
45, 49 in series, and as a result the air supply line 90 is
generally C-shaped. From the last of the air springs 49, the air
supply line 90 connects to a pressure relief valve 106 which
prevents pressure inside the system from exceeding a predetermined
level. The pressure relief valve 106 is provided since the
compressor 100 is constantly running and as a result, supplies air
to the air spring system faster than is required to replace the air
that escapes the air springs 45, 49.
Turning now to FIGS. 5 and 6, the air compressor 100 and its
operation will be described in more detail. The air compressor 100
has a body 110 defining a main chamber 112 and a sub-chamber 114
that selectively fluidly communicate together via passage 116. A
check valve consisting of a spring 118 and a disk 120 is disposed
inside the sub-chamber 114. The spring 118 biases the disk 120
against the passage 116 so as to selectively prevent air flow from
the main chamber 112 to the sub-chamber 114 via the passage 116.
Air inlets 122 formed in the body 110 fluidly communicate the main
chamber 112 with the atmosphere. Air outlets 124 formed in the body
110 fluidly communicate the sub-chamber 114 with the accumulator
chamber 104. A piston 126 is disposed inside the main chamber 112.
A wheel 128 having an integrally formed axle 130 is disposed inside
the top of the piston 126 with the ends of the axle 130 extending
out of the sides of the piston 126. The axle 130 passes through
slots 132 formed in the body 110 of the air compressor 100 so as to
guide piston 126 as it reciprocates inside the main chamber 112 as
described below. A collar 134 is disposed around the body 110 and
abuts the ends of the axle 130. A spring 136 is disposed between
the collar 134 and the portion (not shown) of the cover 102
supporting the air compressor 100 so as to bias the piston 126
toward the position shown in FIGS. 5 and 6.
As can be seen in FIG. 3, a compressor driving cam 138 is disposed
on the intake camshaft 50 engages the wheel 128 of the air
compressor 100. As the intake camshaft 50 rotates, the compressor
driving cam 138 pushes on the wheel 128, which in turn moves the
piston 126 towards the passage 116. As it moves, the piston 126
blocks the air inlets 122, and as result the air pressure inside
the main chamber 112 increases as the volume of the main chamber
112 decreases. When the air pressure inside the main chamber 112
becomes high enough to overcome the bias of the spring 118, the
disk 124 moves away from the passage 116, thus allowing the
pressurized air to flow from the main chamber 112 to the
sub-chamber 114 via the passage 116. From the sub-chamber 114, the
pressurized air flows through the outlets 124 to the accumulator
chamber 104, and from there, to the air springs 45, 49, as
described above. As the intake camshaft 50 continues to rotate, it
no longer pushes on the wheel 128, and the spring 136 biases the
piston 126 back to the position shown in FIGS. 5 and 6 and the
spring 118 biases the disk 120 back against the passage 116. In
this position air can enter the main chamber 112 via the inlets
122. The air compressor 100 continues to operate as described above
for as long as the intake camshaft 50 rotates.
Turning now to FIGS. 7 to 11, another embodiment of a cylinder head
28' and its corresponding elements will be described. For
simplicity, the elements shown in FIGS. 7 to 11 which are similar
to those of FIGS. 1 to 6 have been labelled with the same reference
numerals and will not be described again in detail.
In this embodiment, the air spring system is provided with an air
compressor 100'. The air compressor 100' has the same construction
and operates in the same way as the air compressor 100, except that
the spring 136 abuts a shoulder 140 formed by the body 110' of the
air compressor 100'.
The air compressor 100' is disposed inside the cylinder head 28'.
It is supported inside a holder 150 (FIG. 11) formed on an inner
side of the cover 102'. As with the cover 102, the cover 102' is
fastened over an aperture 152 (FIG. 10) formed in a side wall 30 of
the cylinder head 28'. As can be seen in FIG. 11, the cover 102'
also has an accumulator chamber 104 formed therein.
As in the system described above, from the air compressor 100', the
air flows to the accumulator chamber 104, and from there to the air
springs 45, 49 (in series), and then to the pressure relief valve
106.
The main difference between the system described above and the
current system is in the way the air compressor 100' is driven. In
this embodiment, the compressor driving cam 138 is disposed on a
tubular compressor driving shaft 154. The compressor driving shaft
154 is coaxial with the intake camshaft 50. One end of the intake
camshaft 50 is disposed inside one end of the compressor driving
shaft 154. An overrunning clutch 156 disposed between the end of
the intake camshaft 50 and the compressor driving shaft 154
selectively connects the end of the intake camshaft 50 to the
compressor driving shaft 154 such that the compressor driving shaft
154, and therefore the air compressor 100', can be selectively
driven by the intake camshaft 50. It is contemplated that the air
compressor driving shaft 154 could alternatively be selectively
connected to another rotating shaft of the engine 10, such as the
exhaust camshaft 60 or the crankshaft 14.
A secondary shaft 158, which is coaxial with the compressor driving
shaft 154, has one end disposed inside the other end of the
compressor driving shaft 154. An overrunning clutch 160 disposed
between the end of the secondary shaft 158 and the compressor
driving shaft 154 selectively connects the end of the secondary
shaft 158 to the compressor driving shaft 154 such that the
compressor driving shaft 154, and therefore the air compressor
100', can be selectively driven by the secondary shaft 158. The
secondary shaft 158 is driven by an electric motor 162.
The electric motor 162 is disposed inside a cavity (not shown)
formed between the compressor cover 102' and a second cover 164
(FIGS. 9 and 10) that is fastened to the compressor cover 102'. The
secondary shaft 158 passes through an aperture 166 (FIG. 11) in the
compressor cover 102' and extends inside the cavity. The end of the
secondary shaft 158 that is in the cavity has a gear 168 disposed
thereon. The motor 162 has a motor shaft 170 that extends generally
perpendicularly to the secondary shaft. The motor shaft 170 has a
gear 172 disposed thereon which engages the gear 168 of the
secondary shaft 158 so as to the drive the secondary shaft 158 with
the motor 162.
As would be understood, due to the overrunning clutches 156, 160,
the one of the intake camshaft 50 and the secondary shaft 158 which
rotates the fastest during the operation of the engine 10 is the
one that drives the compressor driving shaft 154, and therefore the
air compressor 100'.
With reference to FIG. 12, a method of operating the system shown
in FIGS. 7 to 11 will be described. The method begins at step 200
when a control unit (not shown) of the engine 10 receives an
indication of a desire to start the engine 10. This indication
could, for example, come from a signal received when an ignition
key is turned or when a start button is pressed. Then at step 202,
before starting the engine 10, the motor 162 is used to drive the
compressor driving shaft 154, and therefore the air compressor
100'. Then at step 204, the control unit determines if a
predetermined condition has been reached. It is contemplated that
the predetermined condition could be a predetermined air pressure
indicative of an air pressure inside the air springs 45, 49. The
air pressure could be sensed by a pressure sensor sensing the
pressure directly inside one or more of the air springs 45, 49, or
inside the air supply line 90. Alternatively, the predetermined
condition could be a predetermined amount of time for which the air
compressor 100' is driven by the motor 162. When the predetermined
condition is reached, the air compressor 100' has supplied enough
air to the air springs 45, 49 such that the air springs 45, 49 bias
the valves 44, 48 towards their closed positions. The motor 162
will continue to drive the air compressor 100' and the engine 10
will not be started until the predetermined condition is reached.
This ensures that the piston 22 of the engine 10 will not contact
the valves 44, 48 when the engine 10 is started, which might have
occurred if air leaked out of the air springs 45, 49 while the
engine 10 was not in use, as previously explained.
Once the predetermined condition is reached, then at step 206 the
engine 10 is started, and as a result, at step 208, the engine 10
drives the air compressor 100' via the intake camshaft 50. The
motor 162 is then stopped at step 210. It is contemplated that the
motor 162 could alternatively be stopped as soon as the
predetermined condition is reached (i.e. between steps 204 and
206). The air compressor 100' continues to be driven by the intake
camshaft 50 until the engine 10 is stopped, at which point the
method ends at step 212.
Turning now to FIG. 13, another air spring system will be
described. For simplicity, the elements shown in FIG. 13 which are
similar to those of FIGS. 1 to 6 have been labelled with the same
reference numerals and will not be described again in detail.
The air spring system shown in FIG. 13 is the same as the one shown
in FIG. 3, but with the addition of a second air compressor 250.
The air compressor 250 is an electrical air compressor powered by a
battery 252. The battery 252 is preferably the same battery that is
used for the engine 10. A switch 254 is used to turn the electrical
air compressor 250 on or off. The electrical air compressor 250 is
preferably disposed inside the cylinder head 28. As can be seen,
the electrical air compressor 250 fluidly communicates with the
accumulator chamber 104, the air supply line 90, and the air
springs 45, 49 so as to supply air to the air springs 45, 49. It is
contemplated that in the case that the air compressor 250 could
bypass the accumulator chamber 104 and connect directly to the air
supply line 90. This could be done should the air compressor 250 be
of a type that provides pressurized air with relatively small
pressure fluctuations.
With reference to FIG. 14, a method of operating the system shown
in FIG. 13 will be described. The method begins at step 300 when a
control unit (not shown) of the engine 10 receives an indication of
a desire to start the engine 10. This indication could, for
example, come from a signal received when an ignition key is turned
or when a start button is pressed. Then at step 302, before
starting the engine 10, the switch 254 is closed and the electrical
air compressor 250 is turned on to supply air to the air springs
45, 49. Then at step 304, the control unit determines if a
predetermined condition has been reached. When the predetermined
condition is reached, the air compressor 250 has supplied enough
air to the air springs 45, 49 such that the air springs 45, 49 bias
the valves 44, 48 towards their closed positions. The air
compressor 250 will continue supply air to the air springs 45, 49
and the engine 10 will not be started until the predetermined
condition is reached. It is contemplated that the predetermined
condition could be a predetermined air pressure indicative of an
air pressure inside the air springs 45, 49. The air pressure could
be sensed by a pressure sensor sensing the pressure directly inside
one or more of the air springs 45, 49, or inside the air supply
line 90, such as pressure sensor 256. Alternatively, the
predetermined condition could be a predetermined amount of time for
which the air compressor 250 is driven.
Once the predetermined condition is reached, then at step 306 the
engine 10 is started, and as a result, at step 308, the engine 10
drives the air compressor 100 via the intake camshaft 50. The
switch 254 is then opened and the electrical air compressor 25
stopped at step 310. It is contemplated that the electrical air
compressor 250 could alternatively be stopped as soon as the
predetermined condition is reached (i.e. between steps 304 and
306). The air compressor 100 continues to be driven by the intake
camshaft 50 until the engine 10 is stopped, at which point the
method ends at step 312.
Modifications and improvements to the above-described embodiments
of the present invention may become apparent to those skilled in
the art. The foregoing description is intended to be exemplary
rather than limiting. The scope of the present invention is
therefore intended to be limited solely by the scope of the
appended claims.
* * * * *
References